Possible Duplicate:
How to check if an email address exists without sending an email?
I'm looking for a way to verify if a particular email address really exists, i.e. not just to make sure that name@domain.com is in the right format, but that bobsmith@gmail.com really exists and isn't made up.
Essentially, I'm looking for some way to implement the same functionality as a website like this: http://verify-email.org/
I'm assuming this would require sending some sort of null email to the mailbox and checking the received response, but I'm not sure how to go about sending a query email without sending a real email.
I haven't been able to find anything that does this - all search results are generally inundated with posts on how to validate that an email is entered in the right format with regex.
Any help appreciated. Thanks!